Binders for bonding wood are used in the manufacture of engineered wood products such as oriented strand board (OSB), flake board, particleboard, veneer, and medium density fiberboard among other products. The cost of the binders is a very significant fraction of the cost of the process or product. Means to decrease the cost of the binder, e.g. by including less expensive components would reduce the cost of the wood product. Moreover, adhesive formulations comprising a combination of urea and formaldehyde structures or a combination of phenol and formaldehyde structures lead to the release of formaldehyde, a regulated chemical designated by the US National Toxicology Program as “known to be a human carcinogen.” Reducing the UF and PF levels in their associated formulations by partially substituting a component that does not release formaldehyde would reduce toxic emissions from the wood product, which would be beneficial both in the manufacturing environment and, where applicable, to the quality of indoor air in contact with the wood product. Substituting synthetic resin with a cheaper alternative has been the subject of much research but generally unsuccessful from a cost:benefit basis as the engineered wood has lacked the desired functional properties. Accordingly, there is a need for a relatively inexpensive component or components that are compatible with existing binder formulation and which can be mixed therein to reduce the cost of the overall formulation and can also reduce formaldehyde emissions during the manufacture and use of the product board.
Attempts have been made to use alternative adhesives for binder compositions. For example, animal based materials, milk-based proteins, and certain types vegetable protein have been used for binder compositions. However, such products have lacked the desired product features, including, durability, water resistance, and strength. Distinctions exist with respect to the vegetable proteins previously used as they have required the modification of vegetable protein by copolymerizing the protein.
This disclosure reveals an unexpected and very useful finding whereby the partial substitution of synthetic resin by unmodified soy flour introduces the cost of the overall resin formulation while reducing toxic emissions and maintaining desired product properties.